1. Field of the Invention
This invention relates to a simplified, rapid method, which is suitable for making a variety of cheeses and cheese products, including natural and processed cheese, in a single installation with common equipment. More specifically, the invention concerns a highly efficient and versatile method for making a variety of cheese and cheese products directly from concentrated milk and other dairy-derived ingredients including dried caseinates, milk protein isolates, and/or milk protein concentrates, and fat from milk, animal, or vegetable-sources.
2. Description of the Related Art
Methods, ingredients and formulations for making natural and processed cheeses by the traditional approach, and related analytical, nutrition and regulatory information are disclosed in "Cheese and Fermented Milk Foods", Vols. I and II, F. V. Kosikowski and V. V. Mistry, 1999. The book titled "Processed Cheese" by V. L. Zehren and D. D. Nusbaum, 1992, describes processed cheese manufacturing, including ingredients, regulations, formulation, processing, packaging and testing. The entire disclosures of these two textbooks are hereby expressly incorporated by reference.
Traditionally, natural and processed cheese, and different styles of cheese within these categories, are made by significantly different processes, using different types of equipment for processing the curd in order to produce cheese with distinctly different physical characteristics. It is an objective of the present invention to provide a method suitable for making a variety of cheese and cheese products with minimal adjustments in the manufacturing technology and equipment.
In the most conventional cheese making processes, the whey proteins of milk, although highly nutritious, are removed from cheese curd in the whey drainage step. Recovery of these whey proteins would improve the efficiency of making cheese and increase yield of cheese. Processed cheese and other pasteurized cheese products use cheese made by conventional means, and, for the most part, also lack the whey protein component from the original milk. Another objective of this invention is to retain the whey proteins in the cheese in order to increase the cheese yield and decrease the by-products from all forms of cheese manufacture.
In order to reduce the by-product stream and improve cheese yield, the cheese and cheese products should retain all or most of the fat, casein, minerals, whey proteins, and as much of the lactose as possible from the milk and milk-derived ingredients. There are three common ways known to recover the whey proteins in the traditional cheese making process.
One way to incorporate whey proteins into cheese has been to collect the soluble whey proteins that are removed from the cheese curd in conventional processing, and apply a heat treatment to aggregate these proteins in a controlled fashion. These aggregates are then added to the next batch of cheese ingredients and incorporated into the cheese by virtue of their being trapped in the cheese matrix. An example of this is provided in U.S. Pat. No. 4,271,201 (Steinne, 1981) which describes a cheese making processes with bacterial cultures and coagulant enzymes used to incorporate separately treated whey protein aggregates into cheese. It is a further object of this invention to incorporate whey proteins, but by a method that does not involve separate isolation of whey proteins and does not involve bacterial cultures and coagulating enzymes, which results in a continuous cycle of whey protein in the by-product stream.
A second way to incorporate whey proteins into cheese has been to concentrate the proteins, or the protein and fat components of milk, using membrane filtration processes, and then produce cheese from this concentrate. There is less protein in the by-products because there is a smaller volume of whey drained from the cheese and because the soluble whey proteins are at a higher concentration in the water phase of the resulting cheese. Examples of this type of approach are U.S. Pat. No. 3,914,435 (Maubois et al, 1975); U.S. Pat. No. 4,205,090 (Maubois et al, 1980); U.S. Pat. No. 4,355,048 (Shaap et al, 1982); U.S. Pat. No. 4,379,170 ( Hettinga et al, 1983); U.S. Pat. No. 4,965,078 (VanLeeuwen et al, 1990); and U. S. Pat. No. 5,356,639 (Jameson and Sutherland, 1994). All of these patents describe processes that utilize bacterial cultures to lower the pH of the concentrate, or an enzyme coagulant to produce the texture required for making cheese. It is yet another object of this invention to produce cheese by utilizing membrane processing for concentrating the proteins and fat of milk but without the need to utilize bacterial cultures or rennet or other enzyme coagulants to produce the desired texture and functionality of cheese.
A third way to incorporate whey proteins into cheese has been to apply a heat treatment or an alkali and heat treatment to the milk-based ingredients in order to cause an association of the whey proteins with the casein proteins. In the subsequent cheesemaking process, the whey proteins are incorporated into the cheese matrix, which matrix in conventional cheesemaking is a casein protein matrix. An example of this approach is U.S. Pat. No. 4,713,254 (Childs and Rajagopalan, 1987).
Conventional cheese making to produce firm or hard cheese utilizes microbial cultures to convert lactose to lactic acid, thus lowering the pH of the cheese relative to the pH of the milk. The culture growth rate is slow enough to produce an evenly distributed hydrogen ion concentration and to avoid localized pH levels that would adversely precipitate the milk proteins and form non-interactive aggregates that will not produce a continuous matrix of the protein, fat, water, minerals, etc. conventionally known as cheese. It is an object of this invention to rapidly and effectively use direct acidification, that is, adding acids to the milk and cheese ingredients in a fashion that avoids variations of a biological origin, such as, changes in enzyme activity during storage, changes in microbial growth rates due to variations in solids and substrate concentrations, changes in pH, and changes in the levels of microbial inhibitors like bacterial phage.
Adjustment of the pH of milk or milk concentrates with organic and inorganic acids is common in the preparation of high moisture cheeses (such as cottage, ricotta, or cream cheese) and in the preparation of relatively high moisture fresh or unripened cheeses such as queso blanco--see Kosikowski and Mistry, Vol. I pages 140-141, Cottage Cheese; Vol. II, pages 64-69, Mozzarella; pages 56-58, Queso Blanco; and pages 72-73, 79, Ricotta for a general description of processing to make these types of cheese. U.S. Pat. No. 4,689,234 (Ernstrom and Brown, 1987) describes a process and apparatus for the production of cheese using ultrafiltration and diafiltration, treating the retentate with an acid, an acid pre-cursor, or a lactic acid-producing starter culture, fermenting, and adding a coagulant enzyme (rennet) to produce curds. The curds are treated to remove moisture, drained, salted, and pressed to obtain the final product. A process for making cottage cheese by direct acidification is described in U.S. Pat. No. 4,066,791 (Corbin, 1978). Direct acidification has also been utilized in the preparation of cheese from ultrafiltered milk. U.S. Pat. No. 4,018,752 (Buhler, 1977). U.S. Pat. No. 4,959,229 (Reddy et al., 1990) describes the preparation of cheese by pre-conditioning milk by lowering the pH to between 6 and 6.6, heat treating, cooling, lowering the pH to between 5 and 6 by direct acidification, inoculating the mix with conventional cheese making bacterial cultures, and treating with a coagulating agent to form a curd which is then treated as in conventional cheese making to produce cheese and a whey by-product. U.S. Pat. No. 5,006,349 (Dahlstrom, 1991) describes the production of a soft cheddar or American-type cheese product by adding lactic acid and rennet enzyme to a milk concentrate prepared by ultrafiltration. A direct acidification step is also described in U.S. Pat. No. 5,130,148 (Brown and Hunt, 1992).
Direct acidification of retentates for cheese base manufacture is also described in the Ph.D. thesis of S. T. Dybing, 1994 (Effect of Whey Protein Incorporation Into Cheddar Cheese Using Ultrafiltration Techniques on Product Yield, Body, and Texture. Volume I, page 127, University Microfilms International, 1994).
These prior art disclosures of direct acidification used to make firm and hard cheeses use coagulating enzymes to form a curd, employ whey drainage, treat curds in lengthy, conventional processing steps, require maturation for flavor development, and are applied to making only one type of cheese. It is a further object of this invention to utilize direct acidification as a rapid process for pH adjustment in conjunction with membrane processing, dry milk ingredient additions, and a single, simple process technique to prepare a variety of cheese types with a variety of functional, physical, and flavor attributes provided primarily by the selection and levels of selected ingredients.
U.S. Pat. No. 5,554,397 (Tanaka and Sueyasu, 1996) describes a process for making processed cheese wherein milk is concentrated by ultrafiltration and diafiltration to produce a composition with the solids in the same proportion as the solids in the final cheese. The retentate is acidified by either bacterial fermentation or by direct acidification with lactic acid and treated with a coagulating enzyme prior to drying. The dried milk product is combined with sodium phosphate (emulsifying salt) and reconstituted in enough water to provide the moisture content of the desired cheese product. The mixture is melted by heating, and flavor, color, and salt are added prior to forming and packaging. An alternative process uses guar and xanthan gums to produce the gelled texture of the processed cheese instead of using the coagulating enzyme treatment. It is an object of this invention to produce the desired texture of semi-hard and hard cheeses and their processed cheese derivatives without the need to employ a coagulating enzyme treatment with all of the milk-derived ingredients, without preparing a milk concentrate with solids in the same proportion as the final cheese, and without the need to use emulsifying salts or non-dairy thickeners to produce the structural and functional properties of a variety of cheese and cheese products.
The structure and physical properties of many types of cheese, mozzarella and cheddar being two examples, are imparted by coagulation of the milk proteins using rennet or other coagulating enzymes. The enzyme treatment of milk modifies kappa casein and produces a coagulum in the presence of calcium ions. This coagulum can be cut and worked by various means to produce the desired structure and function in the cheese. P. F. Fox, in "Developments in Dairy Chemistry", Vol. 4, page 27, 1989, reports that, in typical cheese, an average of 85% of the kappa casein will have been hydrolyzed by the coagulating enzyme. An unexpected benefit of this invention in that the action of coagulating enzymes to modify a major portion of the kappa casein causing aggregation or coagulation is not required. It is an object of this invention to reduce or eliminate the enzyme coagulation step in making cheese thus saving time and minimizing the variation caused by the changes in pH, calcium ion concentration, and enzyme activity. Where a low level of the enzyme rennet was used in the practice of this invention, less than about one-third of the cheese casein was exposed to the enzyme, no coagulation was observed, and the enzyme was denatured prior to packaging the cheese product so as to be inactive during storage of the cheese. Tanaka and Sueyasu (U.S. Pat. 5,554,397 above) describe making cheese without rennet coagulation, but the desired structure was obtained using quar and xanthan gums. It is a further object of this invention to make products that look like and function like cheese without the need to incorporate gums, starches, thickeners, or other structure forming additives into the composition.